Ring gear and mounting assembly therefor

ABSTRACT

A ring gear for driving a rotary apparatus that has an annular flange including radially elongated slots and the gear is bolted to the apparatus along the elongated slots to enable the apparatus to expand and contract, or otherwise deform, without distorting the ring gear.

United States Patent [50] Field ofSearch.....,.,.... i....,..v...................... 74/45OX, 447x, 243X; 263/33CL [72] lnventor William S. Richardson Milwaukee, Wis. Appl. No. 823,755

[56] References Cited UNITED STATES PATENTS 8/1917 Aldrich 1,457,525 6/1923 lsbills..

May 12, 1969 Patented Feb. 9, 1971 [22] Filed Assignee The Falk Corporation Milwaukee, Wis.

a corporation of Wisconsin Primary Examiner-Leonard H. Gerin Attorneys-Donald G. Casser and Adrian L. Bateman, Jr. [54] RING GEAR AND MOUNTING ASSEMBLY THEREFOR 5 Claims, 5 Drawing Figs.

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SHEET 3 BF 3 IINVENTOR WILLIAM s. RICHARDSON ATTORNEY RING GEAR AND MOUNTING ASSEMBLY THEREFOR BACKGROUND OF THE INVENTION 1. Field of the Invention The technical residence of this invention is the art of mounting a ring gear which encircles a rotary apparatus for driving the same in such fashion as to enable the ring gear to maintain its shape and remain properly aligned with its associated driving pinions in spite of physical distortion of the rotary apparatus.

2. Description of the Prior Art I The problem sought to be solved with the present invention is typically encountered with driving apparatusfor cement kilns and will be explained with reference thereto. Cement kilns and the like are extremely long, large diameter tubes lined with refractory materials supported by heavy circumferential rings resting on trunnion roller amounts and driven by a ring gear bolted to a flange on the kiln shell. The ring gear is drivingly connected to a pair of pinions mounted on a foundation and powered by suitable motors and speed reducers for rotating the kiln. The raw materials are introduced at one end and discharged at the other after being cooked during their passage through the kiln by hot gases form the burner section at one end. Since the ring gear surrounds the kiln somewhat near its middle, the gears are generally split into 180 segments and bolted together after being assembled about the kiln. The kiln shell, being subjected to extreme temperature changes, expands, contracts, becomes egg-shaped and may undergo other physical deformation, thereby putting heavy stress on the split bolts holding together the ring gear segments. In consequence, even with the heaviest practical prestressed bolting, the splits between the gear segments, which pass down through the root between two adjacent teeth, have a tendency to open up to thereby increase the space between the teeth and induce fatigue fractures due to impact loading as a driving pinion crosses the split.

Several solutions to the above problem are revealed in the patent literature. U.S. Pat. No. 1,184,174 advocates mounting the pinion for driving the ring gear in a movable cradle so that the pinion can follow the ring gear in its irregular motion resulting from distortion of the driven apparatus. U.S. Pat. No. 2,269,700 recommends restricting longitudinal movement of the kiln by a flange near the ring gear that engages wheels mounted on a foundation to direct expansion of the kiln outwardly towards each end, combined with supporting columns designed to accommodate such expansion. A combination of rigidly mounted and resiliently mounted rollers is disclosed in U.S. Pat. No. 2,830,802 which are arranged to restrict movement of the kiln in such fashion as to reduce change in the meshing of the ring gear and its driving pinions. A chain drive utilizing rigidly connected and articulately connected links is presented in U.S. Pat. No. 3,386,718 to accommodate distortion ofthe kiln.

None of the foregoing arrangements has proved entirely satisfactory or particularly efficacious toward solving the problem under consideration, however, and the present invention submits a new concept for its resolution.

SUMMARY OF THE INVENTION Briefly, this invention discloses a ring gear bolted to a flange extending about a rotary apparatus wherein the connecting bolts pass through radially elongated slots formed in the ring gear. The bolts are thereby permitted to move radially within the slots if the apparatus distorts, but this will not impair the driving alignment of the ring gear. Special washers are also shown for use in conjunction with a ring gear of the above construction that are particularly adapted for facilitating installation of such ring gears.-

A principle object of the invention as to mount a ring gear relative to its driven apparatus such that the apparatus can move radially under the effects of physical distortion, but such movement will not affect the shape of the ring gear. Another principle object is to provide means for mounting a ring gear on its driven apparatus that will accommodate relative movement between the apparatus and the ring gear. A more specific object is to provide the particular apparatus hereinafter described and claimed.

DESCRIPTION OF THE DRAWINGS The ensuring description sets forth the details ofthe present invention, in terms sufficient to instruct persons skilled in the art as to its practice, by reference to an illustrated embodiment and discussion of some permissible variations, it being understood that the description is intended to illustrate, not limit, this invention and that other embodiments and variations not specifically discussed are possible within the scope of the present invention. In the drawings:

FIG. 1 is a side view of a cement kiln driven by a ring gear mounted in accordance with the principles of this invention;

FIG. 2 is an end view of the ring gear;

FIG. 3 is a sectional view of a portion of the ring gear illustrating its attachment to the kiln when it is ready to be operated, and FIG. 4 is a similar view showing an initial step during installation of the gear;

FIG. 5 is an enlarged view showing a connecting bolt used to attach the ring gear to the kiln; and

FIG. 6 is a diagrammaticview to illustrate the effects of distortion of the kiln with the ring gear ofthis inventionv DESCRIPTION OF PREFERRED EMBODIMENTS FIG. 1 illustrates a rotary cement kiln 10 comprising a long cylindrical body mounted for rotation in an inclined position. The lower end of the kiln 10 is inserted with a hood 11 that encloses the combustion apparatus and the upper end of the kiln extends into a chamber 12 where raw materials are fed into the kiln through hopper 13. A plurality of rings 14 are attached to the kiln at spaced intervals along its length and engage trunnion mounted rollers I5 to support the kiln in its desired position.

The kiln 10 is rotated by motor 16 driving a speed reducer 17 that is connected through coupling 18 to pinion 19 which meshes with the ring gear 20, there usually being two such pinions 19 on opposite sides of the ring gear but only one is visible in FIG. I.

The apparatus as described to this point is of the usual construction and, except to illustrate a typical field of use. forms no part of the present invention which is directed to the construction of the ring gear 20 and the manner in which it is attached to the kiln.

In FIG. 2 the ring gear.20 of this invention has two segments 20a and 2% which are bolted together to form an annular gear. The ring gear is attached by a plurality of spaced connecting bolts 25 to an annular flange or collar 26 attached to the kiln 10. There are 24 connecting bolts shown in the drawings, but this number can be varied to suit the particular apparatus. Each connecting bolt 25 passes through a slot 27 formed in the annular gear flange 28, the slots being shaped, according to this invention, to allow radial movement of the connecting bolts 25 and including, see particularly slot 270, spaced parallel sidewalls 29 and 30 connected by a curved end wall 31 in the particular form shown herein. The slots thus have a U-shaped configuration with the sidewalls 29 and 30 having their inner ends opening onto the innermost periphery of the gear flange 28 and their outer ends connected by the end wall 31. Other shapes for the slots can also be used, eg radially elongated ovals. The slots 27 have an open end along the innermost edgeof the gear flange 28. A washer 32, whose structure is described in detail below, is associated with each bolt 25 and a nut 33 is threaded onto each bolt to hold the gear in placev FIGS. 3-5 illustrate in further detail the construction of the ring gear 20 of this invention and its new mode of attachment to the kiln 10. Each connecting bolt 25 passes through a spacer block 35 which is inserted within a slot 27. The spacer block 35 includes a circular head 36 which is positioned between the kiln flange 26 and the gear flange 28 and extends beyond the sidewalls 29 and 30 of the slot 37, see FIG 5. There may be a slight clearance on the order of .002 inches- .003 inches between the head of the spacer block and the surface of the gear flange. With further reference to FIG. 5, a spacer block 35 also includes a body portion 37 that extends through a slot 27, which body portion 37 has flattened sides 38 and 39 adjacent walls 29 and 30 respectively of the slot, the walls 38 and 39 being slightly spaced therefrom (about .002 inches-.003 inches) to allow the body of the spacer block to slide within the slot.

The washers 32, see now FlGS. 3 and 4, include a flat head 40 and an annular flange 41. When the ring gear 20 is first attached to the kiln in an unloaded condition and after all connecting bolts 25 are loosely inserted between the gear flange 28 and the kiln flange 26, the washers 32 are positioned as illustrated in FIG. 4 in which condition the annular flange 41 of each washer contacts the gear flange 28 and clamps the gear into position as the gear is being adjusted to its proper alignment. The inner diameter of the flange 41 is larger than the diameter of the adjacent end 42 ofthe spacer block so that the washer can contact the gear in this fashion. Approximately every third bolt 25 is reamed to a precision fit with its hole through the kiln flange 26 and its hole through the spacer block 35 after the desired gear alignment has been obtained and while the washers 32 are in the position of FIG. 4, this is to provide for the transmission of the driving torque. The remaining bolts 25, however, need only have a loose fitting with their corresponding flange and spacer block holes. Once this alignment has been achieved, the washers 32 are reversed to the position illustrated in FIG. 3 in which their heads 40 contact the end 42 of each spacer block 35 in the particular position achieved during the alignment process. This construction of the washer 32 therebyfacilitates alignment and installation of the ring gear 20 and is also adapted for satisfactory running after alignment has been obtained. Shims may be added between the spacer blocks and the washers as are necessary for suitable alignment.

A grease fitting 45 is attached to each bolt 25 and communicates with an axial grease passage 46 connected to a radial grease passage 47 for supplying lubricating grease between the bolts 25 and the spacer blocks 35.

The diagram of FIG. 6 illustrates the effects of distortion of the kiln 10 when loaded with a charge 50 on the relative position of the kiln and ring gear 20. This will be described with reference to bolts 25a, 25b, 25c and 25d, the other bolts being omitted from the diagram for the sake of clarity. Before any distortion takes place, the bolts 25a, 25b, 25c and 250' are in their solid-line positions of FIG. 6. Assuming-the weight of the charge 50 is sufficient to cause the kiln 10 to change its shape slightly or the kiln distorts due to thermal effects, a slight eggshaped configuration will result in which the kiln will elongate along its vertical axis and shorten along its horizontal axis. The bolts 25a and 25c will move in an outward radial direction relative to the center of the kiln, along their respective slots 27 in the gear flange, to their dotted line positions indicated by the letter x in FIG. 6. Concurrently, the bolts 25b and 25d will move radially inwardly toward the center of the kiln 10, also moving along their respective slots 27, to their dotted line positions indicated by the letter y. This movement of the kiln in relation to the ring gear is made possible by the elongated slots in the gear flange through which extend the connecting bolts joining in the gear to the kiln flange. The flattened sides of the spacers 35 arranged as illustrated in FIGS. 3-5 aid in guiding such movement along the slots. Movement along other axes is accommodated in the same fashion. This movement, which may be very slight and on the order of a few thousands of an inch, prevents distortion of the ring gear by reason of expansion and contraction of the kiln, or other radial distortion of the kiln, and also prevents the imposition of stress on the bolts holding together the two segments of the ring gear due to any such radial distortion.

here has thus been described a ring gear according to this invention which includes a gear flange having a plurality of spaced slots that are elongated in the radial direction and which accommodate connection bolts for joining the ring gear to a flange or similar structural portion of the apparatus to be driven by the gear. The connecting bolts are adapted for radial movement within such elongated slots under the influence of radial deformation of the apparatus to which the gear is connected. As another feature, the bolts extend through spacer members which are inserted within the elongated slots of the gear flange and flat sides ofthe same configuration as the sides of the slots for guiding movement of the bolts thereulong. Washers of a particular configuration especially adapted to facilitate installation and subsequent running of the apparatus also have been described.

I claim: 7

1. in a ring gear of the type have an inner annular flange which is to be joined by connecting bolts to an apparatus to be driven by the ring gear, the improvement wherein:

a plurality of slots are defined in the flange of the ring gear,

there being one slot for each connecting bolt; and

each slot is radially elongated to accommodate radial movement ofa connecting bolt therein.

2. A ring gear according to claim 1, wherein each slot comprises a generally U-shaped opening comprising spaced parallel straight sidewalls with their inner ends opening onto the innermost periphery of said annular flange of the ring gear, and an end wall connecting the opposite ends ofthe sidewalls.

3 An apparatus ofthe type including l a rotary apparatus including an annular flange, (2) a ring gear encircling the apparatus for driving it and having an annular gear flange. and (3) connecting bolts extending between the annular flange of the apparatus and the gear flange for connecting the gear to the apparatus, the improvement wherein: (l) the ring gear includes a plurality of slots defined along the gear flange, there being one slot for each connecting bolt, and each slot is radially elongated; and the connecting bolts are adapted to radial movement within the elongated slots.

4. Apparatus according to claim 3, further including a spacer member inserted in each elongated slot and through which each connecting bolt extends, said spacer member including sidewalls arranged to engage sidewalls of the slots during radial movement ofthe connecting bolts within the slot.

5. Apparatus according to claim 4, further including a washer on each connecting bolt, said washer having a flat head portion and a circumferential flange extending thereabout, said circumferential flange being larger than the spacer member in each slot and adapted to contact the gear flange during installation and alignment of the gear, and said head of each washer being adapted to contact an end of a spacer member after installation of the apparatus. 

1. In a ring gear of the type have an inner annular flange which is to be joined by connecting bolts to an apparatus to be driven by the ring gear, the improvement wherein: a plurality of slots are defined in the flange of the ring gear, there being one slot for each connecting bolt; and each slot is radially elongated to accommodate radial movement of a connecting bolt therein.
 2. A ring gear according to claim 1, wherein each slot comprises a generally U-shaped opening comprising spaced parallel straight sidewalls with their inner ends opening onto the innermost periphery of said annular flange of the ring gear, and an end wall connecting the opposite ends of the sidewalls.
 3. An apparatus of the type including (1) a rotary apparatus including an annular flange, (2) a ring gear encircling the apparatus for driving it and having an annular gear flange, and (3) connecting bolts extending between the annular flange of the apparatus and the gear flange for connecting the gear to the apparatus, the improvement wherein: (1) the ring gear includes a plurality of slots defined along the gear flange, there being one slot for each connecting bolt, and each slot is radially elongated; and the connecting bolts are adapted to radial movement within the elongated slots.
 4. Apparatus according to claim 3, further including a spacer member inserted in each elongated slot and through which each connecting bolt extends, said spacer member including sidewalls arranged to engage sidewalls of the slots during radial movement of the connecting bolts within the slot.
 5. Apparatus according to claim 4, further including a washer on each connecting bolt, said washer having a flat head portion and a circumferential flange extEnding thereabout, said circumferential flange being larger than the spacer member in each slot and adapted to contact the gear flange during installation and alignment of the gear, and said head of each washer being adapted to contact an end of a spacer member after installation of the apparatus. 